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Topic Review (Newest First)

10-16-2007 07:24 AM

Tartan34C

Quote:

Originally Posted by SVArgo

Sapperwhite,

I believe that it is still LaFiell mast, not 100% though, I'll know about 0930 tomorrow. I actually tried to do a quick calculation based on LaFiell's information in the link you sent, but they didn't give the units on the moment of inertia, so I'm not quite sure if its coming out right. I've got some mast section data at work that I'll check tomorrow and see if I can't figure out how much tension would be required for a couple inches of rake.

At any rate, the one I believe the boat is fitted with is the OM3D, very beefy as you note. Definitely not a floppy racing rig!

I believe the moment of inertia Lefiell quotes is in inches to the fourth power. That also matches what I have for some other similar sections. And just a side trip into terminology. I think rake refers to the amount the mast tilts so a 3” rake would mean the masthead is 4” aft of the step. That rake would be the same if the mast had a bow in it or not. It just refers to how far the masthead is displaced compared to the heel or step. I think your rig does have some small amount of rake, 2 or 3 inches, but again it’s not a bendy rig and it needs to be straight between the step and masthead.
All the best,
Robert Gainer

PS. Lots of Yacht Clubs and small yards will step a mast but don’t have the expertise to tune or service one. They will step a mast that has obvious defects without even seeing them. Even in a “good” yard the owner should at least check the mast before steeping and if possible be there to be sure everything goes well. And it goes without saying you need to be aware of your masts condition and how the rig is tuned at all times. Its makes for a bad day if you drop the rig even if you are in sight of home and offshore it may become life threatening.

10-16-2007 02:57 AM

Sapperwhite

Quote:

Originally Posted by RickBowman

I will abandon this thread as it has been hijacked.

Good, abandon away. I don't see how discussing stepping the mast is concidered a hijack, after all that was the OPs topic, remember? At least some of us are offering up advice and useful links pertaining to the subject matter, whereas some others are not, so who's hijacking Rick? And I said I wasn't going to get into a battle over it.....

RR, enjoy SVArgo and welcome to the PSC family. Great boats. You may also find some info in the Yahoo groups, but I think that the 37 group is pretty dead. The Dana and Flicka groups are very active, and can offer up some good advice on certain items even though they are different boats. A few things translate through much of the PSC line.

10-15-2007 10:58 PM

Sapperwhite

Quote:

Originally Posted by RickBowman

You have leaped from the thread of yard work to offshore rig probems? This thread is asking for information of a boat delivery setup and nothing about offshore incidents. I have never been to a yard that would allow me to be aboard when the mast is being put on or removed. That is a professional yard, a safe yard. If you want to steal a thread, please start a new one, thank you.

Rick, I'm not going to get into a battle over. I have had my mast stepped at a professional yard, and I demanded to be a part of the stepping evolution. They said it was absolutly fine with them, and I was a part of the process. "Standing there with hands in pockets" is bad advice any way you cut it. You're welcome.

10-15-2007 10:45 PM

SVArgo

PCS 37 Mast

Quote:

Originally Posted by Sapperwhite

SVArgo,
Robert hit it on the head with this. The PSC masts are built like a telephone pole. You'd have to put a considerable amount of over tension on the rigging to get any real amount of bend in it.

Do you have the LeFiell mast, or did PSC change the vendor in more recent models?tml[/url]

Sapperwhite,

I believe that it is still LaFiell mast, not 100% though, I'll know about 0930 tomorrow. I actually tried to do a quick calculation based on LaFiell's information in the link you sent, but they didn't give the units on the moment of inertia, so I'm not quite sure if its coming out right. I've got some mast section data at work that I'll check tomorrow and see if I can't figure out how much tension would be required for a couple inches of rake.

At any rate, the one I believe the boat is fitted with is the OM3D, very beefy as you note. Definitely not a floppy racing rig!

10-15-2007 07:19 PM

Sapperwhite

Quote:

Originally Posted by Tartan34C

I think the mast on that boat wants to be straight so donít let the racing crowd or the dock walkers talk you into pretending that you have a bendy rig. You are a designer so you know what Euler said and the rules about long slender columns and buckling.

All the best,
Robert Gainer

SVArgo,
Robert hit it on the head with this. The PSC masts are built like a telephone pole. You'd have to put a considerable amount of over tension on the rigging to get any real amount of bend in it.

This is the yards responsibility and they should/better know what they are doing. You should be standing aside with your hands in your pockets, watching and learning.

No offense Rick, but I would have to say that's pretty bad advice. Is it the yards responsibility when you are offshore and the rig fails? They won't be there to save your ass, you're all alone at that point. I make a point of it to know as much as possible about how everything on Jessica Anne works for just that reason. One day it could be just me; no yard to blame, no cell phone to call some rigger and bitch at them, no help but what I can do for myself. I try my hardest not to leave my destiny in the hands of some yardboy that doesn't really know what he's doing.

10-15-2007 10:37 AM

SVArgo

No Hands in pockets for me...

Rick,

In this case, the yard's scope of work is for crane operation for an hour or two and perhaps one yard hand to help physically move the mast around and rig it to the crane. So the yard is not really responsible for the rig or its tuning beyond the liability of the crane operation.

In any case, I'll have the benefit of the previous owner in town to help out, and with the good background information and recommendations by the respondents to this thread, I should be amply fore warned and armed.

10-14-2007 12:12 PM

SVArgo

Thanks Robert,

It sounds pretty straightforward. You're right that there isn't any rake to the mast, she stands up pretty straight. I think I'll save a couple of nickels and do without the gauge.

New Orleans and Naval Architects? The names have a certain symmetry. But, it is where the work is predominantly. The oil patch, the shipyards, its all between Houston and Jacksonville, and New Orleans is smack dab in the middle. There are a couple of Naval Architecture firms left in New York, Gibbs & Cox, Sparkman & Stevens, Rosenblatt & Sons, and a couple of others, but not like in the heyday when the Brooklyn Naval Yard was still open and Gibbs was employing almost 2000 people to do the design and drafting work on its big projects. There are still quite a few around Newport, assuming you meant Newport News, VA, but not too many left in RI. Besides, the sailing season is longer.

If you poke around a bit you should find a thread that deals with tuning the rig of your boat (including a link to a PDF file for the PSC37 rig tuning guide).

Good luck with your new boat!

10-14-2007 08:59 AM

Tartan34C

Nothing special about rigging that one. Just like any boat start with the headstay and backstay to set the rake. Then the uppers to put the masthead in the center. Now fill in with the lowers etc to get the stick straight and then sail the boat to tune her. Sighting along the sailtrack is a good reference for straight. Some people use a Loos gauge to set the tension with different amounts of preload in the wire depending on how you feel about preload and how you were taught to tune but I find that the pluck approach works well with the final tuning done under sail.

If you do decide to use the gauge approach Loos recommend a preload of 15% of the wires breaking strength for the headstay and in a masthed rig they say to use 10 to 12% for the upper and lower shroud while in a fractional rig they recommend as much as 20% if the shrouds have a lot of drift aft of the mast and contribute to headstay tension. Something that doesn’t apply in your case. In no case should you exceed 25% of the wires breaking strength. And I think you need slightly more tension in the upper then the lower for both the masthead and fractional rig. The upper is longer so it will stretch more then the lower if you start out with equal tension in both wires. But as I said the pluck approach is simple and works well after very little practice.

I think the mast on that boat wants to be straight so don’t let the racing crowd or the dock walkers talk you into pretending that you have a bendy rig. You are a designer so you know what Euler said and the rules about long slender columns and buckling.

What is it with New Orleans and Navel Architects? A friend of mine, Chris McKesson, who is also a Naval Architect and live-aboard on a Columbia 36 is moving in January 2008 to New Orleans and will be teaching a course in the Practical Design of Advanced Marine Vehicles at the University of New Orleans. It seams like there are more NA and ME in New Orleans now then in Newport or New York.
All the best,
Robert Gainer

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